intracoronal bleaching Flashcards
what is calcific metamorphosis and how does it affect tooth colour
it is the reaction to tooth concussion or subluxation leading to deposition of dentine in pulp and root canal space, giving a yellow discolouration
defn of intra coronal bleaching
the use of chemical oxidizing agents within the coronal portion of an endodontically treated tooth to remove tooth discoloration
how does bleaching work
the bleach breaks down into smaller molecules which have less or no colour
types of bleaching techniques
1) thermo (thermal catalytic) / photo bleaching
- place a base over root fill
- place 30-35% h2o2 into the canal and heat bleach to 50-60 degrees for max 5 mins. either plunge red hot instrument into bleach or use heat from lamp that activates the h2o2 to break it down faster
2) walking bleach
- base over root fill
- seal in bleach then let the px go home
indications of bleaching
- discoloration from an interna source
- rct is satisfactory
adv effects of bleaching
- chemical burn of soft tisue (must do under RDI)
- external root resroption bc h2o2 can diffuse through dentinal tubules and exit through cemental defects but this is usually for when we use h2o2 without a base
- decreased mechanical properties of dentine
- decreased CR bodning
predisposing factors of cervical resorption
- heat (thermocatalytic technique)
- prior dental trauma
- prior ortho
- pt <25 yo because wider dentinal tubules
- no cervical seal aka no base
how will h2o2 affect CT bond and how to remedy it
- o2 polymerisation inhibition
- diminished resin tags
- increase porosity
- lower bond strength
to remedy:
- restore tooth only after 2 weeks
- remove surface enamel
- neutralise with catalase or sodium ascorbate (ascorbic acid)
how many times before we expect a change in shade
- most change in tooth colour occurs after first session
- incrementally less change occurs with each subsequent session
- no further improvement likely after 4 changes of bleach
choices of bleaching agents
1) sodium perborate
- forms h2o2 in water
2) carbamide peroxide
- forms h2o2 in water
- in itself is more stable than h2o2
3) h2o2 itself
